Mario Ancic has been forced to retire from tennis at 26 after a series of injuries and illnesses. The Croat, who reached No7 in the world in 2006, announced his decision on Wednesday in Split.

"I'm forced to quit because nature has decided it's time," he said. "My back can't withstand the effort of professional tennis." Ancic had also struggled against knee problems as well as glandular fever.

Ancic, known for his powerful serves, reached the Wimbledon semi-finals in 2004 but never won a major. He won three singles titles and five doubles titles on the tour, while also helping Croatia to win the 2005 Davis Cup and taking bronze with Ivan Ljubicic in the doubles at the Olympics in 2004.

He now plans to become a lawyer, having completed a law degree at the University of Split in 2008.